Method of cementation of boron into the surface of iron or steel



subject of the Emperor Patented Nov. 6, 1923.

OFFICE.

METHOD OF CEMENTATION OF BORON No Drawing.

To all whom it may concern:

Be it known that I, TAKEO MIYAcUcHI,

of Japan, and resident of Sendagayamachi, 'loyotamagori. 'l'okyofu, Japan, have invented certain new and useful Improvements in the Methods of (ementation of Boron into the Surface of Iron or Steel, of which the following is a specification.

My invention relates to cementation of boron into any desired surface of iron or steel and has for one object the production of a tough and hard surface on metal which is to be utilized in making articles of excellent quality such as bolt heads, knife blades. razor blades, chiscls or the like. A further object of the invention is to minimize the wear and tear of the friction surface of shafts. gear wheels. ball hearings or the like.

It has been hitherto proposed to cement carbon into the surface of iron or steel. which process is usually termed carbon cementation. but, as far as I am aware, there has been no good process for cementat-ion of boron into the surface of iron or steel.

The fact that iron or steel. when combined with boron, becomes tough and hard. has been recently discovered. In order to attain the resulting advantage, it is my invention to convert the desired surface of iron or steel into boron steel for the purpose of making excellent bolt heads or knife edges or the like.

My invention is as follows First, clean the desired surface of iron or steel where boron is to be cemented, and then shield the remaining portion with iron plate or iron powder or clay in order to prevent the action of boron, and place it. within finely powdered ferro-boron, in a closed furnace. Then heat the furnace up to about. 800 or 900 C. in the presence of chlorine gas which is fed continuously into the furnace. whereby boron contained in the ferro-boron enters into the surface of the treated iron or steel, to a certain depth.

To give an example of my tests I fed chlorine which prepared iron was placed, underjua pressure of one to two atmospheres and heated the furnace to about 900 C. After one and one-half hours, iron was obtained on the surface of which boron cementation was effected to a. thickness of about one millimetre.

gas into a furnace within INTO THE SURFACE OF IRON OR STEEL.

Application filed October 19, 1921. Serial No. 508,819.

In this process it is obvious that if desired, a mixture of boron oxide or boron compound and carbon powder may be used in place of ferro-boron.

As to the action of the chlorine gas in this method, it is my belief that chlorine gas combines with boron to form boron chloride gas which comes into contact with the surface of iron or steel being treated. The boron in the boron chloride at a high temperature becomes cemented to the iron or steel, thereby liberating chlorine. It should be noted that. cementat-ion of boron into the surface of iron or steel by diffusion is not so effective as is the present method and that I have succeeded in obtaining the cementation to a depth of one millimetre as above described which extent is notattainable by p eviously known method.

This method can be accomplished likewise on the surface of special metals such as metals containing chromium, silicon. nickel, manganese. tungsten. molybdenum or the like.

\Vhat I claim 1. A method for the cementation of boron into the surface of iron or steel, comprising, placing the iron or steel within a closed furnace, covering the portion desired to be cemented with a finely powdered boron containing material. shielding the remaining portion with iron plate. iron powder. clay or the like to prevent cementation action of boron, and heating the iron or steel for a considerable period. at from 8tltl-900 (l. in the presence of chlorine gas.

2. The method of claim 1, said boron containing material, being ferro-boron.

3. The method of claim 1, said boron containing material. being boron-oxide.

4. The method of claim 1. said boron containingmaterial, being boron containing material and carbon powder.

5. The method of claim 1, as applied to ferrous-alloys.

Signed at the embassy of the United States of America in the Empire of Japan this 26th day of September. A. I). 1921.

1n presence of two witnesses.

TAKEO MIYAGUCHI.

Witnesses:

Krcono WATANAKO, EUGENE H. DOOMAN. 

